The United Nations' chief weapons inspector Hans Blix is to brief French and British leaders on Friday, as the inspections process in Iraq acquires a new sense of urgency.

Blix: asking for more time for inspectors

The forthcoming meetings with French President Jacques Chirac and British Prime Minister Tony Blair follow the discovery on Thursday of what inspectors described as empty warheads designed to carry chemical weapons at a military storage area.

Earlier, Mr Blix called on Iraq to do more to substantiate its claims that it has destroyed banned weapons, or risk a US-led war.

Iraqi President Saddam Hussein warned on Friday that anyone who tries to invade his country will be defeated.

Baghdad defiant

Mr Blix, briefing EU officials in Brussels on Thursday, said Iraq had either to provide evidence - such as archives and budgets - that it had destroyed suspected weapons of mass destruction, or surrender what it might have for destruction.

The US has threatened military action if Iraq is found to have breached a recent UN resolution which obliged it to list all its weapons.

A spokesman for the International Atomic Energy Agency (IAEA), Mark Gwozdecky, told BBC Radio 4's Today programme on Friday that it would be premature to say how significant the warhead find was without proper checks.

Friday is also the 12th anniversary of the American-led air attacks which began the Gulf War.

In a defiant speech to mark the occasion, the Iraqi leader said Baghdad had defended itself with determination 12 years ago, defeating the "evil troops" of dozens of countries.

Anyone who tried to climb over the walls of Baghdad now, he said, would fail in the attempt.

"Baghdad, its people and leadership, is determined to force the Mongols of our age to commit suicide at its gates," the Iraqi leader said, referring to the Mongol armies who sacked the Iraqi capital in 1258.

Mixed messages

The BBC's James Coomarasamy in Paris says France has yet to make any comment on the discovery of the warheads and is likely to reserve judgement for the time being.

IRAQI MATERIAL UNACCOUNTED FOR

Nearly four tons of VX nerve agents

Growth media for 20,000 litres of biological warfare agents

15,000 shells for use in biological warfare

6,000 chemical warfare bombs

Nuclear information

But in the meantime, our correspondent says, Paris is sending mixed messages about the French diplomatic stance in this crisis.

It wants another UN resolution before military force is used against Baghdad - however, Mr Chirac has warned his troops to be prepared for anything in the coming year.

Mr Blair has also been reluctant to comment on Thursday's discovery - Britain and America are waiting for the results of more detailed analysis of the warheads.